| Message ID | 20240816001216.26575-3-dakr@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Generic `Allocator` support for Rust | expand |
On Fri, 16 Aug 2024 02:10:44 +0200 Danilo Krummrich <dakr@kernel.org> wrote: > Separate `aligned_size` from `krealloc_aligned`. > > Subsequent patches implement `Allocator` derivates, such as `Kmalloc`, > that require `aligned_size` and replace the original `krealloc_aligned`. > > Reviewed-by: Alice Ryhl <aliceryhl@google.com> > Reviewed-by: Benno Lossin <benno.lossin@proton.me> > Signed-off-by: Danilo Krummrich <dakr@kernel.org> Reviewed-by: Gary Guo <gary@garyguo.net> > --- > rust/kernel/alloc/allocator.rs | 19 ++++++++++++------- > 1 file changed, 12 insertions(+), 7 deletions(-) > > diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs > index e6ea601f38c6..c83b6dff896d 100644 > --- a/rust/kernel/alloc/allocator.rs > +++ b/rust/kernel/alloc/allocator.rs > @@ -8,6 +8,17 @@ > > struct KernelAllocator; > > +/// Returns a proper size to alloc a new object aligned to `new_layout`'s alignment. > +fn aligned_size(new_layout: Layout) -> usize { > + // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first. > + let layout = new_layout.pad_to_align(); > + > + // Note that `layout.size()` (after padding) is guaranteed to be a multiple of `layout.align()` > + // which together with the slab guarantees means the `krealloc` will return a properly aligned > + // object (see comments in `kmalloc()` for more information). > + layout.size() > +} > + > /// Calls `krealloc` with a proper size to alloc a new object aligned to `new_layout`'s alignment. > /// > /// # Safety > @@ -15,13 +26,7 @@ > /// - `ptr` can be either null or a pointer which has been allocated by this allocator. > /// - `new_layout` must have a non-zero size. > pub(crate) unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: Flags) -> *mut u8 { > - // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first. > - let layout = new_layout.pad_to_align(); > - > - // Note that `layout.size()` (after padding) is guaranteed to be a multiple of `layout.align()` > - // which together with the slab guarantees means the `krealloc` will return a properly aligned > - // object (see comments in `kmalloc()` for more information). > - let size = layout.size(); > + let size = aligned_size(new_layout); > > // SAFETY: > // - `ptr` is either null or a pointer returned from a previous `k{re}alloc()` by the
diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs index e6ea601f38c6..c83b6dff896d 100644 --- a/rust/kernel/alloc/allocator.rs +++ b/rust/kernel/alloc/allocator.rs @@ -8,6 +8,17 @@ struct KernelAllocator; +/// Returns a proper size to alloc a new object aligned to `new_layout`'s alignment. +fn aligned_size(new_layout: Layout) -> usize { + // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first. + let layout = new_layout.pad_to_align(); + + // Note that `layout.size()` (after padding) is guaranteed to be a multiple of `layout.align()` + // which together with the slab guarantees means the `krealloc` will return a properly aligned + // object (see comments in `kmalloc()` for more information). + layout.size() +} + /// Calls `krealloc` with a proper size to alloc a new object aligned to `new_layout`'s alignment. /// /// # Safety @@ -15,13 +26,7 @@ /// - `ptr` can be either null or a pointer which has been allocated by this allocator. /// - `new_layout` must have a non-zero size. pub(crate) unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: Flags) -> *mut u8 { - // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first. - let layout = new_layout.pad_to_align(); - - // Note that `layout.size()` (after padding) is guaranteed to be a multiple of `layout.align()` - // which together with the slab guarantees means the `krealloc` will return a properly aligned - // object (see comments in `kmalloc()` for more information). - let size = layout.size(); + let size = aligned_size(new_layout); // SAFETY: // - `ptr` is either null or a pointer returned from a previous `k{re}alloc()` by the